class ActiveSupport::HashWithIndifferentAccess
Implements a hash where keys :foo
and
"foo"
are considered to be the same.
rgb = ActiveSupport::HashWithIndifferentAccess.new rgb[:black] = '#000000' rgb[:black] # => '#000000' rgb['black'] # => '#000000' rgb['white'] = '#FFFFFF' rgb[:white] # => '#FFFFFF' rgb['white'] # => '#FFFFFF'
Internally symbols are mapped to strings when used as keys in the entire
writing interface (calling []=
, merge
, etc). This
mapping belongs to the public interface. For example, given:
hash = ActiveSupport::HashWithIndifferentAccess.new(a: 1)
You are guaranteed that the key is returned as a string:
hash.keys # => ["a"]
Technically other types of keys are accepted:
hash = ActiveSupport::HashWithIndifferentAccess.new(a: 1) hash[0] = 0 hash # => {"a"=>1, 0=>0}
but this class is intended for use cases where strings or symbols are the
expected keys and it is convenient to understand both as the same. For
example the params
hash in Ruby on Rails.
Note that core extensions define Hash#with_indifferent_access
:
rgb = { black: '#000000', white: '#FFFFFF' }.with_indifferent_access
which may be handy.
To access this class outside of Rails, require the core extension with:
require "active_support/core_ext/hash/indifferent_access"
which will, in turn, require this file.
Private Class Methods
# File lib/active_support/hash_with_indifferent_access.rb, line 96 def self.[](*args) new.merge!(Hash[*args]) end
# File lib/active_support/hash_with_indifferent_access.rb, line 64 def initialize(constructor = {}) if constructor.respond_to?(:to_hash) super() update(constructor) hash = constructor.to_hash self.default = hash.default if hash.default self.default_proc = hash.default_proc if hash.default_proc else super(constructor) end end
# File lib/active_support/hash_with_indifferent_access.rb, line 87 def self.new_from_hash_copying_default(hash) ActiveSupport::Deprecation.warn(" `ActiveSupport::HashWithIndifferentAccess.new_from_hash_copying_default` has been deprecated, and will be removed in Rails 5.1. The behavior of this method is now identical to the behavior of `.new`. ".squish) new(hash) end
Private Instance Methods
Same as Hash#[]
where the key passed as argument can be either
a string or a symbol:
counters = ActiveSupport::HashWithIndifferentAccess.new counters[:foo] = 1 counters['foo'] # => 1 counters[:foo] # => 1 counters[:zoo] # => nil
# File lib/active_support/hash_with_indifferent_access.rb, line 180 def [](key) super(convert_key(key)) end
Assigns a new value to the hash:
hash = ActiveSupport::HashWithIndifferentAccess.new hash[:key] = 'value'
This value can be later fetched using either :key
or
'key'
.
# File lib/active_support/hash_with_indifferent_access.rb, line 109 def []=(key, value) regular_writer(convert_key(key), convert_value(value, for: :assignment)) end
# File lib/active_support/hash_with_indifferent_access.rb, line 289 def convert_key(key) key.kind_of?(Symbol) ? key.to_s : key end
# File lib/active_support/hash_with_indifferent_access.rb, line 293 def convert_value(value, options = {}) if value.is_a? Hash if options[:for] == :to_hash value.to_hash else value.nested_under_indifferent_access end elsif value.is_a?(Array) if options[:for] != :assignment || value.frozen? value = value.dup end value.map! { |e| convert_value(e, options) } else value end end
# File lib/active_support/hash_with_indifferent_access.rb, line 260 def deep_stringify_keys; dup end
# File lib/active_support/hash_with_indifferent_access.rb, line 258 def deep_stringify_keys!; self end
# File lib/active_support/hash_with_indifferent_access.rb, line 264 def deep_symbolize_keys; to_hash.deep_symbolize_keys! end
# File lib/active_support/hash_with_indifferent_access.rb, line 77 def default(*args) arg_key = args.first if include?(key = convert_key(arg_key)) self[key] else super end end
Removes the specified key from the hash.
# File lib/active_support/hash_with_indifferent_access.rb, line 253 def delete(key) super(convert_key(key)) end
Returns a shallow copy of the hash.
hash = ActiveSupport::HashWithIndifferentAccess.new({ a: { b: 'b' } }) dup = hash.dup dup[:a][:c] = 'c' hash[:a][:c] # => nil dup[:a][:c] # => "c"
# File lib/active_support/hash_with_indifferent_access.rb, line 216 def dup self.class.new(self).tap do |new_hash| set_defaults(new_hash) end end
Returns true
so that Array#extract_options!
finds
members of this class.
# File lib/active_support/hash_with_indifferent_access.rb, line 52 def extractable_options? true end
Same as Hash#fetch
where the key passed as argument can be
either a string or a symbol:
counters = ActiveSupport::HashWithIndifferentAccess.new counters[:foo] = 1 counters.fetch('foo') # => 1 counters.fetch(:bar, 0) # => 0 counters.fetch(:bar) { |key| 0 } # => 0 counters.fetch(:zoo) # => KeyError: key not found: "zoo"
# File lib/active_support/hash_with_indifferent_access.rb, line 194 def fetch(key, *extras) super(convert_key(key), *extras) end
Checks the hash for a key matching the argument passed in:
hash = ActiveSupport::HashWithIndifferentAccess.new hash['key'] = 'value' hash.key?(:key) # => true hash.key?('key') # => true
# File lib/active_support/hash_with_indifferent_access.rb, line 162 def key?(key) super(convert_key(key)) end
This method has the same semantics of update
, except it does
not modify the receiver but rather returns a new hash with indifferent
access with the result of the merge.
# File lib/active_support/hash_with_indifferent_access.rb, line 225 def merge(hash, &block) self.dup.update(hash, &block) end
# File lib/active_support/hash_with_indifferent_access.rb, line 60 def nested_under_indifferent_access self end
# File lib/active_support/hash_with_indifferent_access.rb, line 272 def reject(*args, &block) return to_enum(:reject) unless block_given? dup.tap { |hash| hash.reject!(*args, &block) } end
Replaces the contents of this hash with other_hash.
h = { "a" => 100, "b" => 200 } h.replace({ "c" => 300, "d" => 400 }) # => {"c"=>300, "d"=>400}
# File lib/active_support/hash_with_indifferent_access.rb, line 248 def replace(other_hash) super(self.class.new(other_hash)) end
Like merge
but the other way around: Merges the receiver into
the argument and returns a new hash with indifferent access as result:
hash = ActiveSupport::HashWithIndifferentAccess.new hash['a'] = nil hash.reverse_merge(a: 0, b: 1) # => {"a"=>nil, "b"=>1}
# File lib/active_support/hash_with_indifferent_access.rb, line 235 def reverse_merge(other_hash) super(self.class.new(other_hash)) end
Same semantics as reverse_merge
but modifies the receiver
in-place.
# File lib/active_support/hash_with_indifferent_access.rb, line 240 def reverse_merge!(other_hash) replace(reverse_merge( other_hash )) end
# File lib/active_support/hash_with_indifferent_access.rb, line 267 def select(*args, &block) return to_enum(:select) unless block_given? dup.tap { |hash| hash.select!(*args, &block) } end
# File lib/active_support/hash_with_indifferent_access.rb, line 310 def set_defaults(target) if default_proc target.default_proc = default_proc.dup else target.default = default end end
# File lib/active_support/hash_with_indifferent_access.rb, line 259 def stringify_keys; dup end
# File lib/active_support/hash_with_indifferent_access.rb, line 257 def stringify_keys!; self end
# File lib/active_support/hash_with_indifferent_access.rb, line 263 def symbolize_keys; to_hash.symbolize_keys! end
Convert to a regular hash with string keys.
# File lib/active_support/hash_with_indifferent_access.rb, line 278 def to_hash _new_hash = Hash.new set_defaults(_new_hash) each do |key, value| _new_hash[key] = convert_value(value, for: :to_hash) end _new_hash end
# File lib/active_support/hash_with_indifferent_access.rb, line 265 def to_options!; self end
Updates the receiver in-place, merging in the hash passed as argument:
hash_1 = ActiveSupport::HashWithIndifferentAccess.new hash_1[:key] = 'value' hash_2 = ActiveSupport::HashWithIndifferentAccess.new hash_2[:key] = 'New Value!' hash_1.update(hash_2) # => {"key"=>"New Value!"}
The argument can be either an
ActiveSupport::HashWithIndifferentAccess
or a regular
Hash
. In either case the merge respects the semantics of
indifferent access.
If the argument is a regular hash with keys :key
and +“key”+
only one of the values end up in the receiver, but which one is
unspecified.
When given a block, the value for duplicated keys will be determined by the
result of invoking the block with the duplicated key, the value in the
receiver, and the value in other_hash
. The rules for
duplicated keys follow the semantics of indifferent access:
hash_1[:key] = 10 hash_2['key'] = 12 hash_1.update(hash_2) { |key, old, new| old + new } # => {"key"=>22}
# File lib/active_support/hash_with_indifferent_access.rb, line 140 def update(other_hash) if other_hash.is_a? HashWithIndifferentAccess super(other_hash) else other_hash.to_hash.each_pair do |key, value| if block_given? && key?(key) value = yield(convert_key(key), self[key], value) end regular_writer(convert_key(key), convert_value(value)) end self end end
Returns an array of the values at the specified indices:
hash = ActiveSupport::HashWithIndifferentAccess.new hash[:a] = 'x' hash[:b] = 'y' hash.values_at('a', 'b') # => ["x", "y"]
# File lib/active_support/hash_with_indifferent_access.rb, line 204 def values_at(*indices) indices.collect { |key| self[convert_key(key)] } end
# File lib/active_support/hash_with_indifferent_access.rb, line 56 def with_indifferent_access dup end